As apparatuses for drying wet hands after hand-washing, hand drying apparatuses are available that make use of a high-speed airstream for blowing away the water drops attached to the hands. In such an apparatus, in a main box body forming an outer casing, a hand insertion portion in a hollow shape is provided as a processing space. In the hand insertion portion, an air nozzle is disposed and to the air nozzle, an air duct is joined. In turn, the air duct is connected to an air blower (high-pressure airstream generating device) that blows a high-pressure airstream into the hand insertion portion. During a hand drying operation, the water blown away inside the hand insertion portion is drained into a drain tank disposed beneath the hand insertion portion via a water pan, which is disposed at the bottom of the hand insertion portion. Herein, Patent Literature 1 and Patent Literature 2 are referred to for the disclosure of relevant conventional technologies.    Patent Literature 1: Japanese Patent Application Laid-open No. H11-244192    Patent Literature 2: Japanese Patent Application Laid-open No. 2001-327433